Is Pluto a planet or not? Depending the age of whom you ask, and depending they keep up with the latest new, they might answer yes or now. Apparently, it also depends whether you’re asking an astronomer or a planetary scientists. At least that’s the sentiment that NASA scientists, led by New Horizon principal investigator Alan Stern, is giving off in proposing a redefinition of what a planet is, which would re-induct Pluto to the club once again. Curiously enough, it would also add 100 new planets to our solar system alone.